This study exploits the use of readily available human alloimmune sera to study the effects of serum antibody mediated injury to isolated components of the blood vessel wall; namely, cultured endothelium and smooth muscle. Such sera contain antibody directed against cell surface antigens specific for endothelial cells (anti-E) and probably also for smooth muscle (anti-SM). Using the highly sensitive peroxidase-anti-peroxidase (PAP) method, we will establish the frequency of anti-E and anti-SM antibody in alloimmune sera, study their relationship to morphologic vascular injury, and derive sera for allotyping human vascular endothelium and smooth muscle. Using PAP methods and electronmicroscopy we will quantitate the relative densities of important groups of cell surface self, non-self recognition antigens on autologous smooth muscle cells, endothelial cells and lymphocytes. The capacity of smooth muscle cells to stimulate a lymphocyte proliferative response and to function as a target for complement-dependent cytotoxic antibody, antibody-dependent cell mediated cytolysis and direct cell mediated cytolysis will be compared with similar capacities of autologous endothelium and lymphocytes. We will study and quantitate any loss of surface antigenicity of smooth muscle and endothelial cells in prolonged culture and compare such findings with any changes in capacity to incite, or be a target for, the immune mechanisms above, and any changes from normal in cell function and morphology. Using the PAP method and a panel of specific sera, we will survey and map the distribution and relative density of groups of cell surface self recognition antigens in all major vascular segments within the kidney and other selected blood vessels from heart, lung, liver, etc.